Timing mechanism



UNITED STATES PATENT OFFICE.

WOLFGANG E. SCHWARZMANN, 0E LONGMEADOW, MASSACHUSETTS, ASSIGNOR TO,

AMERICAN BOSCH MAGNETOCORPORATION, OF NE JV YORK, N. Y., A CORPORATIONor New YORK.

TIMING MECHANISM.

Specification of Letters Patent. Patent d pl 30 1922 Application filedDecember 11, 1920. Serial No. 430,015.

T 0- all whom it may] concern:

Be it known that I, WOLFGANG E. SonwAnzMANN, a citizen of the UnitedStates, residing at Longmeadow, in the county of Hampden, State ofMassacl'iusetts, have invented certain new and useful ImprovementsinfTiming Mechanism; and I do hereby declare the following to be a full,clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

The present invention relates to adjustable timing devices for magnetos,and particularly one adapted to be carried by the interrupter housing ofthe magneto.

An ignition system almost invariably provides variable timing; periodsto suit different speed and load conditions imposed upon the engine withwhich it is assocated. To that end, the mechanical interrupter-of themagneto or sparking coil has an adjustable member towhich is attached .atiming member connected by an adjusting rod or wire to the control leveron the steering wheel or post of an automotive vehicle or a convenientpart of a stationary organization. Heretofore, it has been customary tofasten a timing arm to the adjustable member of the illterrupter by ascrew or other securing means for rigidly connecting them together, butin such arrangement the adjusting pull on the control. lever is appliedat a single point of the periphery of theadjustable member'and sometimescauses the adjustable memberto bindfin its bearing, particularly if adecided increase in the rcsistai'icedevelops in the bearing.

her to be located on one side or the other of the adjustable member ofthe interrupter, or

above or below it, or at some intermediate point, in order that thecontrol lever may be attached to it most con eniently, The adjustablemember ordinarily in the form. of a ring carrying cams whichareperiodically engaged by the dcflectable element of a pair of contactcarrying elements. These cams are accurately positioned and fastened inthe adjustable member, or cam' ring,by the manufacturer oftheinterrupter, and therefore, the engine builder is frequentlyinconvenienced in installing the magneto or the adjusting rod or wire.To meet this difli culty, the adjustable member or cam ring of theinterrupter has been provided with slots into a selected one of which isset a lug carried by the timing ring surrounding the cam ring, and tothe timing ring is attached a timing arm connected to the rod or wire,as above stated. While this arrangement provides for several positionsof connection, it does not, however, provide for universal relativeangular adjustabillty of r i the timing ring and cam ring, and it alsorequires a thicker adjustable member to provide for the slots. Thisresults as before, in a single point of application of the adjustingpull to the adjustable member. Furthermore, the timing ring isnot'positively prevented from working off iromthe adjustable member inanaxial direction as a result of the continual vibration to whichit issubjected by the engine.

The timing ring is usually rigid or into-- gral with the timing arm,both having a common radial slit to permit a certain amount of flexingof the ring halves and the arm portions on each side of the slit in thearm. A clampingscrew is used to flex the parts so as to clamp the ringhalves upon the periphery of the cam ring. The pres sure thus applied bythe timing ring upon the cam ring forces the lattelf' out of the truecircular shape and a uniform result can never be produced due totheeccentricity of the rings upon the contraction of the split timingring; Furthermore, such timing ring can grip the cam ring at only twopoints, or but a few points, around its circumference instead ofsubstantially the whole circumference or periphery thereof. Suchstructure cannot meet the requirements I I i of providing a connectionadaptedfor all It is often necessary for tlie'tinnngi 1nem''desired/angular relations between the timing arm and the adjustableinterrupter element nor the precise cooperation necessar ily required ina magnetobetween the stationary and rotatable elements oftheinterruptera Vith the above in view and with the object of producinga simpler, cheaper and more e'tlicient device, I have in accordance withone part of my invention, devised an adjustable timing device comprisingan annular band parted or split along a radius thereof and havingradially extending portions at said parting between which is placed anend of a timing arm and to whichsuch end of the arm is attached bysuitable securing" means, the latter acting to ti hten the band aboutthe cam ring on the inter rupter housing in any relative angularposition, the forces, acting to cause the band to tighten, being equallyapplied to the ra dially, extending portions substantially along a planetangential to the periphery of the cam ring at the point or line ofparting so that the binding stress will be imposed upon the band alongits circumference with a resultant uniform distribution of pressurealong the contacting surfaces of the band and cam ring, and with atendency to shorten the circumferential length of the band so as tocause the inner end of the timing arm to be forced radially inwardlyagainst the periphery of the cam ring to more effectively, positivelymaintain the timing arm and cam ring in adjusted relation.

In accordance with another part of the invention the radially extendingportions of the band have reinforcing return-bent portions which giveincreased thickness and rigidity to the radially extending portions.

As another part of the invention, whether or not the radially extendingportions have, although preferably having, reinforcing portions, thetiming arm has one or more tongues located between the radially extendin portions of the band and secured to such portions by suitablesecuring means. the latter serving as a common means for d rawing theradially extending portions toward each. other for a uniformtighteningot the band about the cam ring, as well as for securing suchportions to the end, tongue or tongues of the timing arm and. forradially drawing the inner end of the tongue or tongues into iirmerengagement with the outer surface of the cam ring.

As another part of the invention, whether or not the radially extendingportions have, although preferably having, reintorcing portions, thetiming arm is slitted to provide flexible tongues to which the radiallyextend .ing portions of the band are secured so that as the tongues aretlexed by the securing means the radially ending portions of the handare caused to mutually approach under balanced stresses acting in planessubstazr tially tangential to the periphery of the cam ring so as toproduce a uniform tightening of the band about the cam ring and aninward draw in a radial direction of the inner end of the tongue againstthe periphery ot the ram ring.

in the acci'nnpanying drawing illustratingpreferred and modifiedembodiments of the invention:

Fig. 1 is an end view in elevation of one form of device, constructed inaccordance with myinvention, in connection with. a cam ring of amechanical interrupter" Fig. 9- is a side view of the same: 7 plan viewof the same; Fig. l is verse section of the same; F i

side view of the band; Fig. 6 is a view of a modified form of the bandand timing arm in end elevation; Fig. 7 a top plan view thereof; andFig. 8 is a sectional view.

Referring more particularly to the draw ing the adjustable timing deviceillustrated in F 1 to 5 inclusive, comprises a timingarm 1 having anaperture 2, in which may be connected the timing rod or wire leading tothe steering wheel or other convenient accessible part of the vehicle,and having an end portion 3 preferably in the form of a tongue. Thebinding or clamping ring l is of annular form and is'cut, split orparted along a radius thereof so that the band may expand or contract.The band preferably has integral radially extending portions 5, at thepoint of parting, between which is located the tongue 3 of the timingarm, a securing means, such as a screw bolt 6, passing through suitableapertures provided in both of the radially extending portions 5, and thetongue 3 for rigidly securing said portions and tongue together, as isclearly shown in Fig. 1. Ea ch radially extendingportion preferablyprovided with a return-bent portion T folded back upon the portions 5 soas to form therewitha thickened and more rigid extension.

It will be apparent that the tongue is relatively thin so that theportions 5 may be located as practically near to each. other as possiblewhereby as the binding screw or bolt causes the members 5 to niuitual2117])1'O2L0ll, the forces acting upon the band 4: to contact its sizewill not substantially in a plane tangential to the periphery of the camring 8 at the point or line of parting of the band 4-. It will furtherbe noted that the securing bolt or screw serves both. purposes oftightenin the band upon the cam ring, by causing a relative approach ofthe portions 5, and securing the latter rigidly to the tongue 3 of thetiming arm. It will be further noted that the band lis relatively thinso as to have substantial flexibility for the purpose hereinafter morefully shown.

Referring to the embodiment illustrated in Figs. (3, 7 and S, theadjusting device coinprises a timing arn'i 9 having an aperture .O, forthe reception of an end of a timing rod or wire leading to a convenientaccessible part of the vehicle, and a slit ll. cut into one end of thearm so as to provide tongues 12 on each side of the slit, the tonguesbeing capable of flexing under suitable stress, The l'GlZLtlVOl) thinand flexible band 13 preferably has integral radially extending portions14; disposed in spaced parallel. relation and secured upon the outersurfaces of the tongues 12 by a suitable securing means, such as abinding screw or bolt 15 passing through and operative in suitableapertures provided in the portions 14: and tongues 12.

As the securing screw is operated the tongues 12 are flexed to mutuallyapproach.

It will be noted that in both forms of dc vice shown the application offorces or stresses is divided equally bet-ween the radially extendingportions since the stresses are applied simultaneously and inopposite directions so that the binding or tightening effect of the band will beequally or uniformly distributed throughout the surfaces of contactbetween the band and the cam ring. The forces or stresses are appliedclose to the periphery of the cam ring so that as the ends of the bandare drawn together these forces will not substantially along a planetangential to the cam ring at the point or line of separation betweenthe ends or radially extending portions of the band, so that theresultant forcesacting through the band will be substantially along thecircumference of the band. As the band is contracted there is a tendencyto shorten its circumferential length and hence is circular sizewhereupon the inner ends of the tongue 3 or tongues 12 are drawninwardly radially against the surface of the cam, ring for firmengagement therewith, such engagement becoming greater upon the greatertendency to contract the band. In use, the band in expanded condition isplaced over the cam ring and the tongue or tongues of the timing arminserted between the radially extending portions of the band after whichthe securing means or screw is inserted in place. Just before tighteningthe securing means the timing arm and the band is rotated to any desiredangular position with respect to the cam ring before contracting theband upon the cam ring, thus providing a universal adjustment of thedevice relative to the cam, ring, and hence, the interrupter elements.The screw is then tightened to contract the band about the cam ring andto cause the radially extending portions to bind with the tongue ortongues of the timing arm and to firmly engage the periphery of the camring, the securing means serving as a common means for both functions ofcontracting the band and of securing the timing arm to the radiallyextending portions of the band. Inasmuch as the band is relatively thinit will not offer resistance to flexing action so as to merely cause theband to contact at but a few points upon the periphery of the cam ring,but will have a tendency to deliver the forces along the band so thatpressure is applied uniformly and evenly throughout the surfaces ofcontact between the band and my invention what prising an interrupterhousing having a cam ring the combination of an annular band partedalong a radius thereof and having radially extending portions at theparting thereof,a timing arm having an end there of between saidportions and means for securing said portions to said end of said armand for tightening said band about said ring.

2; In a timing device for magnetos comprising an interrupter housinghaving a cam ring, the combination of an annular band parted along aradius thereof and having radially extending portions at the partingthereof, a timing arm having an end thereof between said portions,saidportions having reinforcing return-bent portions, and means forsecuring said reinforced portions to said end of said arm and fortightening said band about said ring.

3. In a timing device for magnetos eomprising an interrupter housinghaving a cam ring, the combination of an annular band parted along aradius thereof and havingradially extending portions at the partingthereof, a timing arm having a tongue between said portions and meansfor securing said portions to said tongue and for tightening said bandabout said ring.

i. In a timing device for magnetos comprising an interrupter housinghaving a cam ring, the combination of an'annular band parted along aradius thereof and having radially extending portions at the partingthereof, a timing arm having a tongue located between said portions,said portions having reinforcing return-bent portions, and means forsecuring said reinforced portions to said tongue and for tightening saidband about said ring. v

5. In a timing device for magnetos comprising an interrupter housinghaving a. cam ring, the combination of an annular bandv parted along aradius thereof and having radially extending return-bent portions at theparting thereof a timing arm having a tongue between said portions, andcommon means for moving said portions toward each other for tighteningsaid band about said ring and for securing said portions to said tongueand in tightened position.

6. In a timing device for magnetos comprising an interrupter housinghaving a cam ring, the combination of an annular band parted along aradius thereof and having radially extending portions adjacenttheparting thereof, a slitted. timing arm having flexible tongues adjacentthe slit thereof and located between said portions and means forsecuring said ends to said tongues and for fiexinv said tongues fortightening said band about said ring.

' In testimony whereof I aflix my signature.

WOLFGANG E. SC HWARZMANN.

